Welcome to London's underworld where cops don't deal, criminals don't bargain and crime bosses don't negotiate. Meet Mark Hammond and Frank Carter: One a former gangster and convicted bank robber, the other a vigilante cop. They're two men on opposite sides of the law but joined in their obsession to bring down London's crime supreme - Charlie Jolson. Jolson's reigned London's streets for 26 years, but out here - no one stays on top forever.